Study design: Secondary analysis of a clinical trial.
Objectives: To perform a secondary analysis on the effects of neuromuscular electrical stimulation resistance training (RT) combined with testosterone replacement therapy (TRT) compared with TRT on the untrained muscles after spinal cord injury (SCI).
Setting: Medical research center.
Methods: Twenty-two men with chronic motor complete SCI were randomized into TRT + RT group (n = 11) or TRT group (n = 11). Both groups received 16 weeks of TRT (2-6 mg/day) via testosterone patches. The TRT + RT group received twice weekly progressive RT of the knee extensor muscles using electrical stimulation and ankle weights. Magnetic resonance images were captured to measure cross-sectional areas (CSAs) of trunk, glutei, and leg muscles.
Results: Total and absolute gluteus maximus m. (14%, P = 0.003 and 16%, P = 0.001), gluteus medius m. (10%; P = 0.008 and 14%; P = 0.02), and total glutei m. (8%, P = 0.01 and 11%, P = 0.005) CSAs increased overtime for the TRT + RT group. Mean between-group differences of 2.86 (95% CI: 0.30, 5.4), 1.89 (95% CI: 0.23, 3.58) and 5.27 (95% CI: 0.90, 9.69) cm2 were noted for absolute gluteus maximus, total gluteus medius and total glutei CSAs, respectively (P < 0.05). Trunk muscle CSAs showed a trend towards an interaction between groups.
Conclusions: RT combined with low-dose TRT results in significant hypertrophy compared with TRT only on the adjacent untrained glutei muscles. Trunk muscles may require direct stimulation to evoke hypertrophy. These exploratory findings may be of clinical relevance in the reduction of incidence and severity of pelvic pressure injuries.